Philomedes ptyx Kornicker 1994

Philomedes ptyx

ETYMOLOGY.—From the Greek ptyx (fold, leaf, layer, plate).

HOLOTYPE.—Adult female on slide and in alcohol in the collection of the Museum of Victoria.

TYPE LOCALITY.—Slope 32, 38°21.90′S, 149°20.00′E, Victoria, S of Point Hicks; depth 1000 m.

PARATYPES.—Slope 69: 1 adult female on slide and in alcohol.

DISTRIBUTION.—Slope 32,1000 m. Slope 69, 1840 m.

DESCRIPTION OF ADULT FEMALE (Figures 42–44a, 109e).—Carapace oval in lateral view, with broad rostrum with straight anterior margin with angular anterior and inferior corners and minute process on inferior corner, small incisur, and small but distinctly projecting caudal process (Figure 42a,c,d). Surface with abundant short pointed bristles (Figure 42b) and scattered longer bristles, some with broad base.

Infold: Rostral infold with 33–35 bristles forming row along dorsal and anterior margins and 2 bristles along ventral margin (Figure 42d); 1 small bristle below inner end of incisur; anteroventral infold with 14 or 15 striae (outermost stria forms list) and 27 or 28 bristles in row (posterior half of row along list); bristles absent along middle part of ventral infold; posteroventral and posterior infold with about 70 small slender bristles along inner margin in groups of 1 to 6 bristles (some shown in Figure 42c); infold of caudal process with anterior flap with 7–10 small bristles along posterior edge (Figure 42c); 3 small bristles just within outer edge of caudal process near dorsal end (Figure 42c).

Carapace Size (length, height in mm): Holotype, 2.86, 1.95, height 68% of length; specimen from Slope 69, 2.90, 2.08, height 72% of length.

First Antenna: 1st joint with slender spines along ventral margin and stouter distal medial spines. 2nd joint with dorsal and ventral spines, medial spines near margins, and 3 bristles (1 ventral, 1 dorsal, 1 lateral) with long spines near midlength. 3rd joint with 1 ventral bristle and 2 dorsal bristles (shortest about length of longest) (Figure 44a). 4th joint with 5 bristles (1 dorsal, 4 ventral). Sensory bristle of 5th joint with 5 proximal and 5 terminal filaments. Medial bristle of 6th joint short, with long proximal and short distal spines. 7th joint: a-bristle broken off both limbs of holotype; remaining bristles typical for genus (bristles missing from right limb, probably due to injury).

Second Antenna: Protopodite bare (Figure 109e). Endopodite 2 jointed (Figure 42e): 1st joint with 6 bare bristles (5 proximal, 1 distal); 2nd joint with 1 ventral bristle with wreaths of long hairs and 1 terminal recurved bare bristle. Exopodite: 1st joint with minute medial terminal bristle; bare bristle of 2nd joint reaching well past 9th joint; bristles of joints 2–5 bare (on holotype bristle of 4th joint broken on left limb and bristles of joint 4 and 5 broken on right limb); bristles of joints 6–8 and 5 (4 long, 1 medium) of 7 bristles on 9th joint broken on both limbs of holotype; longer of 2 short bristles of 9th joint with long spines, shorter with few short spines; joints 3–8 with small basal spines; joints 2–8 with spines on distal dorsal corner (spines of 8th joint long, others minute).

Mandible: Coxale endite large spinous with bifurcate pectinate tip; minute ringed bristle near base of endite. Basale (Figure 42f): medial surface spinous, with 5 proximal bristles (3 pectinate, 2 spinous) and 1 spinous bristle closer to midlength; lateral surface with 5 short spinous bristles (proximal of these actually on ventral margin) (right limb of holotype aberrant in lacking lateral bristles); ventral margin spinous, with 3 distal spinous bristles; dorsal margin with 3 spinous bristles (1 just distal to midlength, 2 terminal). Exopodite about length of dorsal margin of 1st endopodial joint, spinous distally, with 2 subterminal bristles (distal slightly shorter) with long spines at midlength. 1st endopodial joint with 4 ventral bristles (1 short, 3 long, all with long spines) and minute spines on distal dorsal corner. 2nd endopodial joint: dorsal margin with 11 bristles forming roughly 2 groups (5 in proximal group, 6 in distal); ventral margin with 6 short spinous distal bristles in 2 groups, each with 3 bristles; medial surface spinous. 3rd endopodial joint with 4 spinous bristles and 3 bare claws (dorsal claw length of longest claw).

Maxilla: Endite I with 9 bristles; endite II with 6 bristles; endite III long slender with 1 proximal and about 8 terminal bristles. Precoxale and coxale with dorsal fringe of long hairs; coxale with stout plumose dorsal bristle. Basale with 3 long bristles on distal margin. Exopodite short with 3 bristles (1 short slightly proximal, 2 long terminal). 1st endopodial joint with dorsal spines and 1 alpha-bristle with long spines; beta-bristles obscured on both limbs of holotype. 2d endopodial joint obscured on both limbs of holotype but with 3 stout unringed claw-like bristles and additional ringed bristles.

Fifth Limb: Endite I with about 5 bristles; endite II with about 8 bristles; endite III with about 9 bristles. 1st exopodial joint: anterior side with 2 spinous bristles at midwidth and 1 short stout bristle at outer corner (Figure 43a); main tooth with proximal bristle and 4 teeth (distal stouter and with anterior prong; smallest broken off in Figure 43b) (Figure 43a,b). 2nd exopodial joint: inner curvature of large quadrate tooth with 2 small processes (Figure 43b); bristles obscured. 3rd exopodial joint with 3 spinous bristles on inner lobe and 2 with long spines on outer lobe. 4th and 5th exopodial joints fused, with 6 spinous bristles.

Sixth Limb (Figure 43c): With 4 spinous epipodial bristles. Endite I with 3 spinous bristles (2 medial, 1 terminal); endite II with 4 spinous bristles (1 medial, 3 terminal); endite III with 9 spinous bristles (1 medial, 8 terminal); endite IV with 9 or 10 spinous bristles (1 medial, 8 or 9 terminal). End joint prolonged posteriorly, with 25 spinous and hirsute bristles. Lateral and medial surfaces of end joint hirsute; lateral surfaces of endites II-IV with long spines. (Most bristles not shown.)

Seventh Limb: Each limb with 18 bristles (terminal group with 2 on comb side and 3 on peg side; proximal group with 6 on comb side and 7 on peg side); each bristle with up to 7 bells. Terminal comb with 15 alate teeth; side opposite comb with 1 undivided inner peg, 0 or 1 additional undivided peg, and 5 bifurcate pegs (Figure 43d).

Furca (Figure 42g): Each lamella with 12 claws decreasing in length and width and becoming straighter posteriorly along lamella. Claw 1 with stout lateral and medial teeth in rows (several teeth at midlength in lateral row stouter than others; distal medial teeth stouter than lateral teeth); teeth of claws 1–6 markedly stouter than teeth of other claws; claws 6–12 with slender spine-like teeth on anterior and posterior margins near tips. Lamellae near medial side of bases of claws and following claws with long spines; row of long spines on claws near bases. Right lamella anterior to left by width of base of claw 1; anterior margin of right lamella with small spines; medial surface of right lamella near anterior margin with rows of long hairs.

Bellonci Organ (Figure 43f): Elongate with slight indentation just proximal to midlength but suture not evident; tip tapering to small terminal spine; several hairs on tip.

Eyes: Lateral eye minute, barely visible, bare; left eye of USNM 193899 with 2 minute indistinct cells (Figure 43e), but cells not observed in right eye. Medial eye well developed with brown pigment, without long hairs (Figure 43f).

Upper Lip (Figure 43f,g): Hirsute, with 4 minute spines along upper anterior edge, and many glandular openings laterally on anterior projecting part. Proximal lateral glandular field on each side with about 8 small glandular openings; large glandular bodies visible beneath openings in transmitted light (dashed in Figure 43g).

Genitalia (Figure 43h): Small amber-colored round disk on each side anterior to furca.

Anterior of Body (Figure 43f,g): With stout anterior process with blunt tip.

Posterior of Body (Figure 43h): Evenly rounded with hairs along ventral part.

Y-Sclerite (Figure 43h): Typical for genus.

Eggs: Holotype with many fairly large unextruded eggs (2 shown as dashed ovals in Figure 43h).

COMPARISONS.—Only one other species having bifurcate pegs on the 7th lip has been described, P. ramus Kornicker, 1975:277, which is known from a single adult female collected in the Pacific Ocean west of Chile at a depth of 3219 m. The proximal dorsal bristle on the 3rd joint of the 1st antenna is about the length of the joint on P. ptyx (Figure 44a) and longer than the joint on P. ramus (Figure 44b); also, the 7th limb of P. ptyx bears 6 or 7 terminal pegs compared to only 4 for P. ramus. Some additional differences are tabulated below, but variability within each species is unknown.

P. ramus P. ptyx

Carapace length (mm) 3.21 2.86–2.90

Bristles on rostral infold 21 35–37

Bristles on end joint of 6th limb 33 25

Furcal claws 11 12